Parabolic antennas sometimes provide on-the-move communications between a mobile vehicle, such as a land mobile vehicle or an aircraft, and another vehicle, satellite or fixed ground station. Parabolic reflector antennas typically include a parabolic shaped reflector and one or more feed horns that are directed at the reflector. Each feed horn conveys electromagnetic waves between the reflector and a transceiver that is typically housed inside the vehicle upon which the antenna is mounted. The parabolic shaped reflector focuses planar electromagnetic waves incident on the reflector and perpendicular with an axis to a focal point, where the feed horn's aperture is typically located. The parabolic reflector also transforms spherical electromagnetic waves output by the feed horn(s) into a plane wave propagating as a collimated beam.
In order for the parabolic antenna to communicate with a remote device, the antenna beam is pointed at the remote device. That is, the reflector is oriented such that the electromagnetic waves transmitted by the remote device are focused into the aperture of the feed horn(s) and the collimated beam formed by the reflector is directed at the remote device. For on-the-move communications, the antenna beam is continuously steered to compensate for the vehicle's changing orientation. For example, if the parabolic antenna is mounted on an aircraft, the parabolic antenna would be steered to account for the aircraft banking.
One conventional way to steer the antenna beam is to mount the entire parabolic antenna on a two-axis motorized positioning system, such as an elevation-over-azimuth positioner. However, two-axis motorized positioning systems involve two separate rotary joints and/or flexible cables to provide a path for signals to be conveyed between the feed horn(s) and the transceiver. For example, the parabolic antenna may be mounted on an elevation positioner of an elevation-over-azimuth positioner. A first rotary joint would route signals between the transceiver and the azimuth turntable and a second rotary joint would route the signals between the azimuth turntable and the parabolic antenna. These hardware components can be costly and lead to more bulky and complex antenna systems and preclude their use in many applications.
Thus, a need exists in the art for systems and methods that overcome one or more of the above-described limitations.